Izvestiya of Saratov University.
ISSN 1817-3020 (Print)
ISSN 2542-193X (Online)

diffraction halo

Digital Speckle Photography with Correlation Processing of Spatial Spectrum of Specklegram for Determination of Micro Displacement of Scattering Object

The method of digital speckle photography for determining of speckle pattern displacement with sub-pixel accuracy using correlation processing of summary spatial spectrum of speckle patterns is considered in this article. It is assumed that displacement of speckle pattern is caused by deformation or displacement of an object with a scattering surface. The method of phase shift of interference pattern in diffraction halo is proposed for expanding the lower limit of measuring range of speckle pattern displacement to subpixel values.

Technique of Digital Laser Speckle-Photography for Measurement of Scattered Object Microdisplacement

Specklephotography with twoexposition digital recording of specklestructure of diffraction field and numerical specklegram processing for measurements of scattering object micro displacement is considered. Methods for realization of specklephotography technique with recording of digital specklegrams in far field diffraction area and in field of focused image are discussed. Natural and numerical experiments to obtain measuring information on object micro displacement are performed.